In history class, the girl to boy ratio is $4$ to $6$. If there are $24$ boys, how many girls are there?
Explanation: A ratio of $4$ girls to $6$ boys means that there is a group of $4$ girls for every group of $6$ boys. If there are $24$ boys, then there are $4$ groups of $6$ boys each. Because we know the ratio is $4:6$ , there must be $4$ groups of $4$ girls each. There is a total of $16$ girls in history class.